FUNCTION: [Summary is not available for the mouse gene. This summary is for the human ortholog.] This gene encodes a transmembrane protein that is preferentially expressed in the nervous system where it controls neuronal cell survival, differentiation into exons and dendrites, and synaptic plasticity. The encoded protein interacts with membrane receptors, cytosolic signaling components, and cytoskeletal proteins, serving as a scaffold that mediates crosstalk between the neurotrophin pathway and several other intracellular signaling pathways. Aberrant expression of this gene is associated with the onset of various neuropsychiatric disorders and neurodegenerative diseases, including Alzheimer's disease. Naturally occurring mutations in this gene are associated with a syndrome characterized by spastic paraplegia, intellectual disability, nystagmus and obesity. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Feb 2017] PHENOTYPE: Mice homozygous for a knock-out allele exhibit embryonic lethality. Mice heterozygous for a knock-out allele exhibit decreased dendritic complexity in the barrel somatosensory cortex and dentate gyrus neurons. [provided by MGI curators]